Film laminate and interior trim part for motor vehicles

Abstract

The invention relates to a film laminate, including at least one compact decorative layer with a lacquer layer on the upper side and with a foam layer on the underside, where the density of the foam layer is more than 500 kg/m.sup.3. The invention further relates to the use of said film laminate for the coating of components for the interior trim of motor vehicles and to interior trim parts of motor vehicles provided with said film laminate. The foam layer is based on a composition which includes from 15 to 60 parts by weight of at least one thermoplastic vulcanizate, from 15 to 35 parts by weight of at least one high melt strength polyolefin, and from 30 to 60 parts by weight of at least one low density polyethylene (LDPE).

Claims

1. A thermoforming process for producing a film laminate, the process comprising: providing a compact decorative layer comprising a lacquer layer on an upper side, wherein the compact decorative layer further includes an underside; applying a foamable layer directly on the underside of the compact decorative layer, wherein the foamable layer is based on a polymer composition comprising: a) from 15 to 60 parts by weight of at least one thermoplastic vulcanizate (TPV), wherein the at least one TPV comprises a thermoplastic phase and a vulcanized elastomer phase; b) from 15 to 35 parts by weight of at least one high melt strength polyolefin (HMS polyolefin); c) from 30 to 60 parts by weight of at least one low density polyethylene (LDPE); and, d) a chemical blowing agent; wherein proportions of a), b), c) and d) are a total of 100 parts by weight; and wherein the vulcanized elastomer phase of the at least one TPV serves as a phase disruptor that minimizes flow behavior of at least the HMS polyolefin and the LDPE with respect to each other; thermoforming the film laminate, wherein the foamable layer is transformed to a foam layer, and wherein the density of the foam layer is less than 800 kg/m.sup.3; and, crosslinking the film laminate.

2. The thermoforming process as claimed in claim 1, wherein the foamable layer is based on a polymer composition comprising: a) from 35 to 45 parts by weight of the at least one thermoplastic vulcanizate (TPV), b) from 15 to 25 parts by weight of the at least one high melt strength polyolefin (HMS polyolefin); and, c) from 35 to 45 parts by weight of the at least one low density polyethylene (LDPE).

3. The thermoforming process as claimed in claim 1, wherein the at least one high melt strength polyolefin is a high melt strength polypropylene.

4. The thermoforming process as claimed in claim 1, wherein the thermoplastic phase of the TPV is based on polypropylene and the vulcanized elastomer phase of the TPV is based on ethylene-propylene-diene elastomer (EPDM), and wherein the at least one thermoplastic vulcanizate comprises the ethylene-propylene-diene elastomer (EPDM) in an amount of at least 70% by weight.

5. The thermoforming process as claimed in claim 1, wherein the foamable layer is based on a polymer composition which comprises a solid chemical blowing agent.

6. The thermoforming process as claimed in claim 1, wherein the lacquer layer has a thickness less than 10 pm, wherein the compact decorative layer has a thickness from 0.2 to 0.7 mm, and wherein the foam layer has a thickness from 0.5 to 2.0 mm.

7. The thermoforming process as claimed in claim 6, wherein the compact decorative layer has a thickness from 0.4 to 0.6 mm, and wherein the foam layer has a thickness from 0.8 to 1.5 mm.

8. The thermoforming process as claimed in claim 1, wherein the density of the foam layer is more than 500 kg/m.sup.3 and less than 800 kg/m.sup.3.

9. The thermoforming process as claimed in claim 1, wherein the density of the foam layer is from 500 kg/m 3 to 700 kg/m.sup.3.

10. The thermoforming process as claimed in claim 1, wherein after crosslinking the film laminate the film laminate is devoid of lines of weakness.

11. The thermoforming process as claimed in claim 1, wherein during the thermoforming, the film laminate is stretched up to 300%.

12. The thermoforming process as claimed in claim 1, wherein the compact decorative layer is a layer of plastics material.

13. The thermoforming process as claimed in claim 1, wherein an underside of the foam layer includes an adhesive layer.

14. The thermoforming process as claimed in claim 13, wherein the film laminate is attached to a carrier by the adhesive layer on the underside of the foam layer.

15. The thermoforming process as claimed in claim 1, wherein an underside of the foam layer includes a primer.

16. The thermoforming process as claimed in claim 15, wherein the film laminate is attached to a carrier by the primer on the underside of the foam layer.

17. The thermoforming process as claimed in claim 1, wherein the film laminate is used for the coating of components for the interior trim of motor vehicles, in particular at least in the region of the airbag covers or in the region of the tear seams of the airbag covers.

18. The thermoforming process as claimed in claim 1, wherein the film laminate is used for an interior trim part for motor vehicles, the interior trim part being a dashboard.

19. The thermoforming process as claimed in claim 1, wherein the film laminate is arranged at least in a region of an airbag cover and/or in a region of tear seams of the airbag cover.

20. The thermoforming process as claimed in claim 1, wherein the foamable layer is based on a polymer composition comprising a) from 35 to 45 parts by weight of the at least one thermoplastic vulcanizate (TPV), wherein the thermoplastic phase of the TPV is based on polypropylene and the vulcanized elastomer phase of the TPV is based on ethylene-propylene-diene elastomer (EPDM); b) from 15 to 25 parts by weight of the at least one high melt strength polyolefin (HMS polyolefin), wherein the at least one high melt strength polyolefin is a high melt strength polypropylene; and, c) from 35 to 45 parts by weight of the at least one low density polyethylene (LDPE); and wherein the density of the foam layer is more than 500 kg/m 3 and less than 800 kg/m.sup.3.

Description

BRIEF DESCRIPTION OF THE DRAWING

(1) FIG. 1 is a diagram of a film laminate according to an embodiment of the disclosure.

DETAILED DESCRIPTION

(2) The invention will now be explained in more detail with reference to an inventive example, and the single FIG. 1 here is a diagram of the film laminate 1 of the invention with a compact outer layer 2. The thickness of said layer is 0.5 mm. Located on the outer layer 2 there is a lacquer layer 3 with thickness 7 ?m. Located under the outer layer 2 there is the foam layer 4 with the specific polymer composition. The thickness of said layer is 1.0 mm. The film can be used for cladding a motor vehicle dashboard in the region of the passenger airbag. The film laminate 1 has an embossed three-dimensionally structured surface on the decorative layer 2, i.e. a grain applied externally by an embossing roll.

(3) This type of film laminate can be used for the region of airbag covers in interior trim of motor vehicles, with no necessity to provide lines of weakness. It can be processed in thermoforming processes with a high degree of stretching.

(4) Table 1 below lists examples of the polymer compositions for a foam layer 4 with properties thereof (only the foam layer, not the laminate), where I indicates the compositions of the invention and C indicates the comparative mixtures. Tensile strength and tensile strain at break were determined in accordance with DIN 527-3 in longitudinal direction (longitudinally) and transverse direction (transversally) at temperatures relevant for airbag performance. Longitudinal direction and transverse direction here are perpendicular to one another, longitudinal direction being defined as the direction of film production (direction of rolling, direction of extrusion), and transverse direction being defined as the direction perpendicular to the direction of production. The terms tensile strain at break and elongation at break are used synonymously. Test velocity was about 0.2 m/s.

(5) The falling-ball test was carried out in accordance with VDA 237-101 from a height of 230 mm at ?35? C.

(6) The ingredients were as follows: TPV: PP/EPDM blend with 70% by weight of EPDM, MFI 3.0 g/10 min (230? C./2.16 kg), softening point about 165? C. HMS PP: structurally isomeric-modified propylene homopolymer, MFI=10.0 g/10 min at 230? C.; 2.16 kg, melt strength 7 cN at an elongation rate of 250 mm/s measured at a temperature of 200? C. LDPE: Low density polyethylene, MFI=1.9 g/10 min at 190? C.; 2.16 kg; melt strength=34 cN at an elongation rate of 200 mm/s measured at a temperature of 200? C. Blowing agent masterbatch: Hydrocerol 592 (60% by weight of polyethylene and 40% by weight citrates) Stabilizer: UV stabilizer (HALSsterically hindered phenol) Pigment: black colorant made of 85% by weight of polyethylene and 15% by weight of carbon black

(7) The melt flow index (MFI) as used here is determined in accordance with DIN EN ISO 1133 at a temperature of 230? C. and, respectively, 190? C. with a load of 2.16 kg. The terms melt flow index (MFI) and melt flow rate (MFR) are used synonymously.

(8) TABLE-US-00001 TABLE 1 Constituents Unit 1(I) 2(C) 3(I) 4(C) 5(I) TPV Pts. by wt. 20 40 40 20 33.3 HMS PP Pts. by wt. 20 40 20 40 33.3 LDPE Pts. by wt. 60 20 40 40 33.3 Pigment Pts. by wt. 1 1 1 1 1 Stabilizer Pts. by wt. 2 2 2 2 2 Blowing agent Pts. by wt. 2 2 2 2 2 Foam properties Thickness mm 1.07 1.09 1.04 0.93 0.9 Density kg/m.sup.3 621 561 647 590 643 Longitudinal N/mm.sup.2 8.57 9.81 7.56 10.93 8.92 tensile strength at 20? C. Transverse N/mm.sup.2 7.83 8.77 6.7 8.1 7.44 tensile strength at 20? C. Longitudinal N/mm.sup.2 121 102 126 36 87 tensile strain at break at 20? C. Transverse N/mm.sup.2 23 55 57 19 32 tensile strain at break at 20? C. Longitudinal N/mm.sup.2 2.49 5.14 2.3 5.26 3.68 tensile strength at 85? C. Transverse N/mm.sup.2 2.27 4.16 2.19 3.72 2.86 tensile strength at 85? C. Longitudinal N/mm.sup.2 300 823 229 926 539 tensile strain at break at 85? C. Transverse N/mm.sup.2 109 481 219 228 234 tensile strain at break at 85? C. Longitudinal N/mm.sup.2 13.6 20.9 18 22.4 17.6 tensile strength at ?35? C. Transverse N/mm.sup.2 13.07 20.3 14.2 16.6 16.3 tensile strength at ?35? C. Longitudinal N/mm.sup.2 10.6 13 11.1 7.9 10.5 tensile strain at break at ?35? C. Transverse N/mm.sup.2 9.5 8.1 6.1 4.9 8 tensile strain at break at ?35? C. Falling-ball unacceptable unacceptable acceptable unacceptable unacceptable test at ?35? C. Stretching up acceptable acceptable acceptable acceptable acceptable to 300%

(9) It can be seen from the table that although all of the films are thermoformable, the foam compositions 1(I), 3(I) and 5(I) exhibit reduced and significantly closer values for tensile strain at break and for tensile strength in, respectively, longitudinal and transverse direction, in particular at high and low temperatures. The effect of these closer values is that it is possible to achieve very successful opening of a rectangular airbag flap requiring both longitudinal and transverse fracture of the laminate. The values are also at a level permitting the above. The values for the comparative mixtures are in contrast very different in longitudinal direction and in transverse direction, and in particular at 85? C. the directional differences are extremely large. An airbag flap cannot open as required.

(10) The composition 3(I) moreover leads to a film featuring good low-temperature flexibility, verified by the falling-ball test at ?35? C.